There is a known game apparatus includes an input device having plural transparent boards disposed on a surface of a CRT display, each of four corners of each transparent board being supported by a spring, the input device being provided in an on/off switchable manner by conductive bodies and electrodes displaced from the springs, each screen image on the display is caused to change for each transparent board, and it is competed to see whether or not push-down operation has been performed to the transparent board of a predetermined screen image (for example, cf. a patent document 1). Also, there is a known input device for a game machine where a display device causing a hit target to appear and disappear is disposed on the back surface of a transparent hit board where a plurality of hit detection devices are arranged, such that the display device and the hit board are corresponded to each other on one-to-one (for example, cl. a patent document 2).    Patent Document 1: JP-A-S56-152670    Patent Document 2: JP-A-2000-84233